Cell Physiology Flashcards
What is simple diffusion?
Simple diffusion is a form of diffusion that does not require the assistance of membrane proteins.
How does simple diffusion work?
The particle or substance moves from higher to lower concentration, its movement does not need a membrane protein that will help substances to move downhill.
What is facilitated diffusion?
Facilitated diffusion is the transport of substances across a biological membrane from an area of higher concentration to an area of lower concentration with the help of a transport molecule.
How does facilitated diffusion work
Facilitated diffusion is the passive movement of substances, such as biological molecules or ions, across a plasma membrane by means of a transport protein located in the plasma membrane. Since the movement of substances is from greater to lesser concentrations, chemical energy is neither used nor required as it would be in active transport.
uWhat factors affect the rate of diffusion across membranes?
Concentration Gradient
Surface Area of the membrane
Size of the molecule
Temperature
Thickness of the exchange surface
How does membrane surface area affect diffusion?
The greater the surface area, the higher the rate of diffusion
How does the size of the molecule affect diffusion
Smaller molecules diffuse faster than large molecules
How does temperature affect diffusion
Higher temperature means higher rate of diffusion
How does the thickness of the exchange surface affect diffusion?
Thinner exchange surfaces allow for higher rates of diffusion
How does concentration gradient affect diffusion?
The greater the concentration gradient, the faster the diffusion
What is active transport?
The movement of molecules from an area of low concentration to an area of high concentration with the use of energy, as it is going against the natural process of diffusion.
